Im noticing a lot of weird stuff with Mac Outlook 2016 when it comes to accepting shared calendar invites (presumably from Windows Outlook users).
Mac users get an invite in Outlook, but the shared calendar never maps/mounts in Outlook on Macs after accepting the invite. Rather, the recipient is taken out of Outlook and into a browser to office.com (the recipient’s O365 web portal). From there, the recipient can accept and view calendar, but it never shows up in Outlook on Mac, and the recipient cant browse/search or manually map the calendar (user cant locate it in GAL, etc). So Outlook NEVER sees the calendar.
What’s REALLY weird is that the same shared calendar DOES appear in Apple's native iOS Mail.app on my iPhone (running iOS 12 beta)!
We are a O365 P1 customer (hybrid).
To see shared calendars on Outlook 2016 you can either add the shared calendar mailbox via Outlook > Preferences > Accounts > Advanced > Add Delegates.
Open shared Calendar and add the mailbox.
For some reason, none of these manual options work. I can locate/discover the user in the GAL, but cant see any Shared calendars (and don't want to map the sender's Inbox).
Here is a screenshot demonstrating what a recipient sees in Outlook 2016 on macOS:
Conversely, here is what a recipient sees in Outlook 2016 on Windows 10:
I am getting the same thing. Just moved to Office 365 and when opening Shared calendar from an invite e-mail, just get an error "SOmething went Wrong, Please try again. After 2 or 3 tries the calendar shows but it is a blank calendar. I can add a new event to the calendar but no existing events will show on the calendar.